/* ----------------------------------------------------------------------
* Copyright (C) 2010 ARM Limited. All rights reserved.
*
* $Date:        15. February 2012
* $Revision: 	V1.1.0
*
* Project: 	    CMSIS DSP Library
* Title:		arm_conv_partial_fast_opt_q15.c
*
* Description:	Fast Q15 Partial convolution.
*
* Target Processor: Cortex-M4/Cortex-M3
*
* Version 1.1.0 2012/02/15
*    Updated with more optimizations, bug fixes and minor API changes.
*
* Version 1.0.11 2011/10/18
*    Bug Fix in conv, correlation, partial convolution.
*
* Version 1.0.10 2011/7/15
*    Big Endian support added and Merged M0 and M3/M4 Source code.
*
* Version 1.0.3 2010/11/29
*    Re-organized the CMSIS folders and updated documentation.
*
* Version 1.0.2 2010/11/11
*    Documentation updated.
*
* Version 1.0.1 2010/10/05
*    Production release and review comments incorporated.
*
* Version 1.0.0 2010/09/20
*    Production release and review comments incorporated.
* -------------------------------------------------------------------- */

#include "arm_math.h"

/**
 * @ingroup groupFilters
 */

/**
 * @addtogroup PartialConv
 * @{
 */

/**
 * @brief Partial convolution of Q15 sequences (fast version) for Cortex-M3 and Cortex-M4.
 * @param[in]       *pSrcA points to the first input sequence.
 * @param[in]       srcALen length of the first input sequence.
 * @param[in]       *pSrcB points to the second input sequence.
 * @param[in]       srcBLen length of the second input sequence.
 * @param[out]      *pDst points to the location where the output result is written.
 * @param[in]       firstIndex is the first output sample to start with.
 * @param[in]       numPoints is the number of output points to be computed.
 * @param[in]       *pScratch1 points to scratch buffer of size max(srcALen, srcBLen) + 2*min(srcALen, srcBLen) - 2.
 * @param[in]       *pScratch2 points to scratch buffer of size min(srcALen, srcBLen).
 * @return Returns either ARM_MATH_SUCCESS if the function completed correctly or ARM_MATH_ARGUMENT_ERROR if the requested subset is not in the range [0 srcALen+srcBLen-2].
 *
 * See <code>arm_conv_partial_q15()</code> for a slower implementation of this function which uses a 64-bit accumulator to avoid wrap around distortion.
 *
 * \par Restrictions
 *  If the silicon does not support unaligned memory access enable the macro UNALIGNED_SUPPORT_DISABLE
 *	In this case input, output, scratch1 and scratch2 buffers should be aligned by 32-bit
 *
 */

#ifndef UNALIGNED_SUPPORT_DISABLE

arm_status arm_conv_partial_fast_opt_q15(
    q15_t* pSrcA,
    uint32_t srcALen,
    q15_t* pSrcB,
    uint32_t srcBLen,
    q15_t* pDst,
    uint32_t firstIndex,
    uint32_t numPoints,
    q15_t* pScratch1,
    q15_t* pScratch2)
{

	q15_t* pOut = pDst;                            /* output pointer */
	q15_t* pScr1 = pScratch1;                      /* Temporary pointer for scratch1 */
	q15_t* pScr2 = pScratch2;                      /* Temporary pointer for scratch1 */
	q31_t acc0, acc1, acc2, acc3;                  /* Accumulator */
	q31_t x1, x2, x3;                              /* Temporary variables to hold state and coefficient values */
	q31_t y1, y2;                                  /* State variables */
	q15_t* pIn1;                                   /* inputA pointer */
	q15_t* pIn2;                                   /* inputB pointer */
	q15_t* px;                                     /* Intermediate inputA pointer  */
	q15_t* py;                                     /* Intermediate inputB pointer  */
	uint32_t j, k, blkCnt;                         /* loop counter */
	arm_status status;

	uint32_t tapCnt;                               /* loop count */

	/* Check for range of output samples to be calculated */
	if((firstIndex + numPoints) > ((srcALen + (srcBLen - 1u)))) {
		/* Set status as ARM_MATH_ARGUMENT_ERROR */
		status = ARM_MATH_ARGUMENT_ERROR;
	} else {

		/* The algorithm implementation is based on the lengths of the inputs. */
		/* srcB is always made to slide across srcA. */
		/* So srcBLen is always considered as shorter or equal to srcALen */
		if(srcALen >= srcBLen) {
			/* Initialization of inputA pointer */
			pIn1 = pSrcA;

			/* Initialization of inputB pointer */
			pIn2 = pSrcB;
		} else {
			/* Initialization of inputA pointer */
			pIn1 = pSrcB;

			/* Initialization of inputB pointer */
			pIn2 = pSrcA;

			/* srcBLen is always considered as shorter or equal to srcALen */
			j = srcBLen;
			srcBLen = srcALen;
			srcALen = j;
		}

		/* Temporary pointer for scratch2 */
		py = pScratch2;

		/* pointer to take end of scratch2 buffer */
		pScr2 = pScratch2 + srcBLen - 1;

		/* points to smaller length sequence */
		px = pIn2;

		/* Apply loop unrolling and do 4 Copies simultaneously. */
		k = srcBLen >> 2u;

		/* First part of the processing with loop unrolling copies 4 data points at a time.
		 ** a second loop below copies for the remaining 1 to 3 samples. */

		/* Copy smaller length input sequence in reverse order into second scratch buffer */
		while(k > 0u) {
			/* copy second buffer in reversal manner */
			*pScr2-- = *px++;
			*pScr2-- = *px++;
			*pScr2-- = *px++;
			*pScr2-- = *px++;

			/* Decrement the loop counter */
			k--;
		}

		/* If the count is not a multiple of 4, copy remaining samples here.
		 ** No loop unrolling is used. */
		k = srcBLen % 0x4u;

		while(k > 0u) {
			/* copy second buffer in reversal manner for remaining samples */
			*pScr2-- = *px++;

			/* Decrement the loop counter */
			k--;
		}

		/* Initialze temporary scratch pointer */
		pScr1 = pScratch1;

		/* Assuming scratch1 buffer is aligned by 32-bit */
		/* Fill (srcBLen - 1u) zeros in scratch buffer */
		arm_fill_q15(0, pScr1, (srcBLen - 1u));

		/* Update temporary scratch pointer */
		pScr1 += (srcBLen - 1u);

		/* Copy bigger length sequence(srcALen) samples in scratch1 buffer */

		/* Copy (srcALen) samples in scratch buffer */
		arm_copy_q15(pIn1, pScr1, srcALen);

		/* Update pointers */
		pScr1 += srcALen;

		/* Fill (srcBLen - 1u) zeros at end of scratch buffer */
		arm_fill_q15(0, pScr1, (srcBLen - 1u));

		/* Update pointer */
		pScr1 += (srcBLen - 1u);

		/* Initialization of pIn2 pointer */
		pIn2 = py;

		pScratch1 += firstIndex;

		pOut = pDst + firstIndex;

		/* First part of the processing with loop unrolling process 4 data points at a time.
		 ** a second loop below process for the remaining 1 to 3 samples. */

		/* Actual convolution process starts here */
		blkCnt = (numPoints) >> 2;

		while(blkCnt > 0) {
			/* Initialze temporary scratch pointer as scratch1 */
			pScr1 = pScratch1;

			/* Clear Accumlators */
			acc0 = 0;
			acc1 = 0;
			acc2 = 0;
			acc3 = 0;

			/* Read two samples from scratch1 buffer */
			x1 = *__SIMD32(pScr1)++;

			/* Read next two samples from scratch1 buffer */
			x2 = *__SIMD32(pScr1)++;

			tapCnt = (srcBLen) >> 2u;

			while(tapCnt > 0u) {

				/* Read four samples from smaller buffer */
				y1 = _SIMD32_OFFSET(pIn2);
				y2 = _SIMD32_OFFSET(pIn2 + 2u);

				/* multiply and accumlate */
				acc0 = __SMLAD(x1, y1, acc0);
				acc2 = __SMLAD(x2, y1, acc2);

				/* pack input data */
#ifndef ARM_MATH_BIG_ENDIAN
				x3 = __PKHBT(x2, x1, 0);
#else
				x3 = __PKHBT(x1, x2, 0);
#endif

				/* multiply and accumlate */
				acc1 = __SMLADX(x3, y1, acc1);

				/* Read next two samples from scratch1 buffer */
				x1 = _SIMD32_OFFSET(pScr1);

				/* multiply and accumlate */
				acc0 = __SMLAD(x2, y2, acc0);

				acc2 = __SMLAD(x1, y2, acc2);

				/* pack input data */
#ifndef ARM_MATH_BIG_ENDIAN
				x3 = __PKHBT(x1, x2, 0);
#else
				x3 = __PKHBT(x2, x1, 0);
#endif

				acc3 = __SMLADX(x3, y1, acc3);
				acc1 = __SMLADX(x3, y2, acc1);

				x2 = _SIMD32_OFFSET(pScr1 + 2u);

#ifndef ARM_MATH_BIG_ENDIAN
				x3 = __PKHBT(x2, x1, 0);
#else
				x3 = __PKHBT(x1, x2, 0);
#endif

				acc3 = __SMLADX(x3, y2, acc3);

				/* update scratch pointers */
				pIn2 += 4u;
				pScr1 += 4u;


				/* Decrement the loop counter */
				tapCnt--;
			}

			/* Update scratch pointer for remaining samples of smaller length sequence */
			pScr1 -= 4u;

			/* apply same above for remaining samples of smaller length sequence */
			tapCnt = (srcBLen) & 3u;

			while(tapCnt > 0u) {

				/* accumlate the results */
				acc0 += (*pScr1++ * *pIn2);
				acc1 += (*pScr1++ * *pIn2);
				acc2 += (*pScr1++ * *pIn2);
				acc3 += (*pScr1++ * *pIn2++);

				pScr1 -= 3u;

				/* Decrement the loop counter */
				tapCnt--;
			}

			blkCnt--;


			/* Store the results in the accumulators in the destination buffer. */

#ifndef  ARM_MATH_BIG_ENDIAN

			*__SIMD32(pOut)++ =
			    __PKHBT(__SSAT((acc0 >> 15), 16), __SSAT((acc1 >> 15), 16), 16);
			*__SIMD32(pOut)++ =
			    __PKHBT(__SSAT((acc2 >> 15), 16), __SSAT((acc3 >> 15), 16), 16);

#else

			*__SIMD32(pOut)++ =
			    __PKHBT(__SSAT((acc1 >> 15), 16), __SSAT((acc0 >> 15), 16), 16);
			*__SIMD32(pOut)++ =
			    __PKHBT(__SSAT((acc3 >> 15), 16), __SSAT((acc2 >> 15), 16), 16);

#endif /*      #ifndef  ARM_MATH_BIG_ENDIAN    */

			/* Initialization of inputB pointer */
			pIn2 = py;

			pScratch1 += 4u;

		}


		blkCnt = numPoints & 0x3;

		/* Calculate convolution for remaining samples of Bigger length sequence */
		while(blkCnt > 0) {
			/* Initialze temporary scratch pointer as scratch1 */
			pScr1 = pScratch1;

			/* Clear Accumlators */
			acc0 = 0;

			tapCnt = (srcBLen) >> 1u;

			while(tapCnt > 0u) {

				/* Read next two samples from scratch1 buffer */
				x1 = *__SIMD32(pScr1)++;

				/* Read two samples from smaller buffer */
				y1 = *__SIMD32(pIn2)++;

				acc0 = __SMLAD(x1, y1, acc0);

				/* Decrement the loop counter */
				tapCnt--;
			}

			tapCnt = (srcBLen) & 1u;

			/* apply same above for remaining samples of smaller length sequence */
			while(tapCnt > 0u) {

				/* accumlate the results */
				acc0 += (*pScr1++ * *pIn2++);

				/* Decrement the loop counter */
				tapCnt--;
			}

			blkCnt--;

			/* The result is in 2.30 format.  Convert to 1.15 with saturation.
			 ** Then store the output in the destination buffer. */
			*pOut++ = (q15_t)(__SSAT((acc0 >> 15), 16));

			/* Initialization of inputB pointer */
			pIn2 = py;

			pScratch1 += 1u;

		}

		/* set status as ARM_MATH_SUCCESS */
		status = ARM_MATH_SUCCESS;
	}

	/* Return to application */
	return (status);
}

#else

arm_status arm_conv_partial_fast_opt_q15(
    q15_t* pSrcA,
    uint32_t srcALen,
    q15_t* pSrcB,
    uint32_t srcBLen,
    q15_t* pDst,
    uint32_t firstIndex,
    uint32_t numPoints,
    q15_t* pScratch1,
    q15_t* pScratch2)
{

	q15_t* pOut = pDst;                            /* output pointer */
	q15_t* pScr1 = pScratch1;                      /* Temporary pointer for scratch1 */
	q15_t* pScr2 = pScratch2;                      /* Temporary pointer for scratch1 */
	q31_t acc0, acc1, acc2, acc3;                  /* Accumulator */
	q15_t* pIn1;                                   /* inputA pointer */
	q15_t* pIn2;                                   /* inputB pointer */
	q15_t* px;                                     /* Intermediate inputA pointer  */
	q15_t* py;                                     /* Intermediate inputB pointer  */
	uint32_t j, k, blkCnt;                         /* loop counter */
	arm_status status;                             /* Status variable */
	uint32_t tapCnt;                               /* loop count */
	q15_t x10, x11, x20, x21;                      /* Temporary variables to hold srcA buffer */
	q15_t y10, y11;                                /* Temporary variables to hold srcB buffer */


	/* Check for range of output samples to be calculated */
	if((firstIndex + numPoints) > ((srcALen + (srcBLen - 1u)))) {
		/* Set status as ARM_MATH_ARGUMENT_ERROR */
		status = ARM_MATH_ARGUMENT_ERROR;
	} else {

		/* The algorithm implementation is based on the lengths of the inputs. */
		/* srcB is always made to slide across srcA. */
		/* So srcBLen is always considered as shorter or equal to srcALen */
		if(srcALen >= srcBLen) {
			/* Initialization of inputA pointer */
			pIn1 = pSrcA;

			/* Initialization of inputB pointer */
			pIn2 = pSrcB;
		} else {
			/* Initialization of inputA pointer */
			pIn1 = pSrcB;

			/* Initialization of inputB pointer */
			pIn2 = pSrcA;

			/* srcBLen is always considered as shorter or equal to srcALen */
			j = srcBLen;
			srcBLen = srcALen;
			srcALen = j;
		}

		/* Temporary pointer for scratch2 */
		py = pScratch2;

		/* pointer to take end of scratch2 buffer */
		pScr2 = pScratch2 + srcBLen - 1;

		/* points to smaller length sequence */
		px = pIn2;

		/* Apply loop unrolling and do 4 Copies simultaneously. */
		k = srcBLen >> 2u;

		/* First part of the processing with loop unrolling copies 4 data points at a time.
		 ** a second loop below copies for the remaining 1 to 3 samples. */
		while(k > 0u) {
			/* copy second buffer in reversal manner */
			*pScr2-- = *px++;
			*pScr2-- = *px++;
			*pScr2-- = *px++;
			*pScr2-- = *px++;

			/* Decrement the loop counter */
			k--;
		}

		/* If the count is not a multiple of 4, copy remaining samples here.
		 ** No loop unrolling is used. */
		k = srcBLen % 0x4u;

		while(k > 0u) {
			/* copy second buffer in reversal manner for remaining samples */
			*pScr2-- = *px++;

			/* Decrement the loop counter */
			k--;
		}

		/* Initialze temporary scratch pointer */
		pScr1 = pScratch1;

		/* Fill (srcBLen - 1u) zeros in scratch buffer */
		arm_fill_q15(0, pScr1, (srcBLen - 1u));

		/* Update temporary scratch pointer */
		pScr1 += (srcBLen - 1u);

		/* Copy bigger length sequence(srcALen) samples in scratch1 buffer */


		/* Apply loop unrolling and do 4 Copies simultaneously. */
		k = srcALen >> 2u;

		/* First part of the processing with loop unrolling copies 4 data points at a time.
		 ** a second loop below copies for the remaining 1 to 3 samples. */
		while(k > 0u) {
			/* copy second buffer in reversal manner */
			*pScr1++ = *pIn1++;
			*pScr1++ = *pIn1++;
			*pScr1++ = *pIn1++;
			*pScr1++ = *pIn1++;

			/* Decrement the loop counter */
			k--;
		}

		/* If the count is not a multiple of 4, copy remaining samples here.
		 ** No loop unrolling is used. */
		k = srcALen % 0x4u;

		while(k > 0u) {
			/* copy second buffer in reversal manner for remaining samples */
			*pScr1++ = *pIn1++;

			/* Decrement the loop counter */
			k--;
		}


		/* Apply loop unrolling and do 4 Copies simultaneously. */
		k = (srcBLen - 1u) >> 2u;

		/* First part of the processing with loop unrolling copies 4 data points at a time.
		 ** a second loop below copies for the remaining 1 to 3 samples. */
		while(k > 0u) {
			/* copy second buffer in reversal manner */
			*pScr1++ = 0;
			*pScr1++ = 0;
			*pScr1++ = 0;
			*pScr1++ = 0;

			/* Decrement the loop counter */
			k--;
		}

		/* If the count is not a multiple of 4, copy remaining samples here.
		 ** No loop unrolling is used. */
		k = (srcBLen - 1u) % 0x4u;

		while(k > 0u) {
			/* copy second buffer in reversal manner for remaining samples */
			*pScr1++ = 0;

			/* Decrement the loop counter */
			k--;
		}


		/* Initialization of pIn2 pointer */
		pIn2 = py;

		pScratch1 += firstIndex;

		pOut = pDst + firstIndex;

		/* Actual convolution process starts here */
		blkCnt = (numPoints) >> 2;

		while(blkCnt > 0) {
			/* Initialze temporary scratch pointer as scratch1 */
			pScr1 = pScratch1;

			/* Clear Accumlators */
			acc0 = 0;
			acc1 = 0;
			acc2 = 0;
			acc3 = 0;

			/* Read two samples from scratch1 buffer */
			x10 = *pScr1++;
			x11 = *pScr1++;

			/* Read next two samples from scratch1 buffer */
			x20 = *pScr1++;
			x21 = *pScr1++;

			tapCnt = (srcBLen) >> 2u;

			while(tapCnt > 0u) {

				/* Read two samples from smaller buffer */
				y10 = *pIn2;
				y11 = *(pIn2 + 1u);

				/* multiply and accumlate */
				acc0 += (q31_t) x10 * y10;
				acc0 += (q31_t) x11 * y11;
				acc2 += (q31_t) x20 * y10;
				acc2 += (q31_t) x21 * y11;

				/* multiply and accumlate */
				acc1 += (q31_t) x11 * y10;
				acc1 += (q31_t) x20 * y11;

				/* Read next two samples from scratch1 buffer */
				x10 = *pScr1;
				x11 = *(pScr1 + 1u);

				/* multiply and accumlate */
				acc3 += (q31_t) x21 * y10;
				acc3 += (q31_t) x10 * y11;

				/* Read next two samples from scratch2 buffer */
				y10 = *(pIn2 + 2u);
				y11 = *(pIn2 + 3u);

				/* multiply and accumlate */
				acc0 += (q31_t) x20 * y10;
				acc0 += (q31_t) x21 * y11;
				acc2 += (q31_t) x10 * y10;
				acc2 += (q31_t) x11 * y11;
				acc1 += (q31_t) x21 * y10;
				acc1 += (q31_t) x10 * y11;

				/* Read next two samples from scratch1 buffer */
				x20 = *(pScr1 + 2);
				x21 = *(pScr1 + 3);

				/* multiply and accumlate */
				acc3 += (q31_t) x11 * y10;
				acc3 += (q31_t) x20 * y11;

				/* update scratch pointers */
				pIn2 += 4u;
				pScr1 += 4u;

				/* Decrement the loop counter */
				tapCnt--;
			}

			/* Update scratch pointer for remaining samples of smaller length sequence */
			pScr1 -= 4u;

			/* apply same above for remaining samples of smaller length sequence */
			tapCnt = (srcBLen) & 3u;

			while(tapCnt > 0u) {
				/* accumlate the results */
				acc0 += (*pScr1++ * *pIn2);
				acc1 += (*pScr1++ * *pIn2);
				acc2 += (*pScr1++ * *pIn2);
				acc3 += (*pScr1++ * *pIn2++);

				pScr1 -= 3u;

				/* Decrement the loop counter */
				tapCnt--;
			}

			blkCnt--;


			/* Store the results in the accumulators in the destination buffer. */
			*pOut++ = __SSAT((acc0 >> 15), 16);
			*pOut++ = __SSAT((acc1 >> 15), 16);
			*pOut++ = __SSAT((acc2 >> 15), 16);
			*pOut++ = __SSAT((acc3 >> 15), 16);

			/* Initialization of inputB pointer */
			pIn2 = py;

			pScratch1 += 4u;

		}


		blkCnt = numPoints & 0x3;

		/* Calculate convolution for remaining samples of Bigger length sequence */
		while(blkCnt > 0) {
			/* Initialze temporary scratch pointer as scratch1 */
			pScr1 = pScratch1;

			/* Clear Accumlators */
			acc0 = 0;

			tapCnt = (srcBLen) >> 1u;

			while(tapCnt > 0u) {

				/* Read next two samples from scratch1 buffer */
				x10 = *pScr1++;
				x11 = *pScr1++;

				/* Read two samples from smaller buffer */
				y10 = *pIn2++;
				y11 = *pIn2++;

				/* multiply and accumlate */
				acc0 += (q31_t) x10 * y10;
				acc0 += (q31_t) x11 * y11;

				/* Decrement the loop counter */
				tapCnt--;
			}

			tapCnt = (srcBLen) & 1u;

			/* apply same above for remaining samples of smaller length sequence */
			while(tapCnt > 0u) {

				/* accumlate the results */
				acc0 += (*pScr1++ * *pIn2++);

				/* Decrement the loop counter */
				tapCnt--;
			}

			blkCnt--;

			/* Store the result in the accumulator in the destination buffer. */
			*pOut++ = (q15_t)(__SSAT((acc0 >> 15), 16));

			/* Initialization of inputB pointer */
			pIn2 = py;

			pScratch1 += 1u;

		}

		/* set status as ARM_MATH_SUCCESS */
		status = ARM_MATH_SUCCESS;

	}

	/* Return to application */
	return (status);
}

#endif	/*	#ifndef UNALIGNED_SUPPORT_DISABLE	*/

/**
 * @} end of PartialConv group
 */
